Motion system with plurality of stewart platform based actuators

ABSTRACT

Examples of a motion system are disclosed. The motion system comprises a plurality of Stewart platform based actuators connected one to each another forming a desired modular configuration. Each of the plurality of actuators is controlled by a central controller that is configured to independently control the plurality actuators and adjust in real time their position, orientation and motion trajectory. The plurality of actuators are arranged in the desired configuration, shape and size to provide motion system that can mimic a natural motion/gait of human or animal body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/751,004, filed Jun. 25, 2015, entitled “MOTION SYSTEM WITH PLURALITYOF STEWART PLATFORM BASED ACTUATORS” which claims the benefit of U.S.Provisional Application No. 62/024,523, filed Jul. 15, 2014, entitled“MOTION SYSTEM WITH PLURALITY OF STEWART PLATFORM BASED ACTUATORS” allof which are hereby incorporated by reference herein in theirentireties.

TECHNICAL FIELD

The present disclosure generally relates to a high performance actuatorsand more particularly relates to a motion system with Stewart platformbased actuators.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

Linear/rotary hexapod (Stewart platform) actuators can be used todirectly mimic a motion of existing industrial (Cartesian) robots andmilling machines but have not been used in motion systems that mimichuman or animal locomotion. Human and animal locomotion can beinfluenced by several factors such as neuromuscular and joint disorderswhich can affect the functionality of joints and can reduce theirmobility. Many individuals with limited mobility require mobilityassistive technologies to keep up with their daily life. A wearableexoskeleton robot is an external structural mechanism with joints andlinks corresponding to those of human body that are synchronized withits motion to enhance or support natural body movements. The exoskeletontransmits torques from its actuators through rigid exoskeletal links tothe human joints and thereby augments human strength. Currently severallower limb exoskeleton mobility assistive devices are known andavailable on the market. For example, the devices developed by ArgoMedical Technologies Ltd. (ReWalk-I™ and ReWalk-P™); Esko Bionics Inc.(eLEG™); Cyberdyne Inc. (HAL™); Rex Bionix (REX™); University ofCalifornia at Berkeley (BLEEXD™), can assist with sitting, turning andclimbing and descending stairs and slopes. All of these mechanisms aredesigned as serial manipulators which consist of a number of rigid linksconnected in serial by the connecting joints which forces each actuatorto support the weight of its successor links and results in a lowpayload-to-weight ratio characteristics with poor force exertioncapabilities. The accuracy in positioning the payload and speed ofmanipulation is another drawback of the known serial robots.

There is a need for a precise and accurate actuators that can be used inmobility assistive devices and/or other robotic applications thatovercome the limitations of the known prior art actuators.

SUMMARY

In one aspect, a motion system is provided. The motion system comprisesa plurality of Stewart platform based actuators connected one to anotherforming a desired modular configuration. The plurality of Stewartplatform actuators comprise an upper plate, a base plate, a plurality ofkinematic legs pivotally connected to the base plate and the upper plateextending therein between and at least one driver in communication withthe plurality of kinematic legs configured to independently drive eachof the plurality of kinematic legs to change length, orientation and/orspeed of the legs, such that a coordinated drive of the plurality oflegs moves one of the plate within six degrees of freedom relative tothe other plate. A system further comprises a central controller thathas an input unit, a processing unit and an output unit. The centralcontroller is in communication with the at least one driver of each ofthe plurality of actuators to independently control length, orientationand/or speed of each of the plurality of kinematic legs of each of theplurality of actuators to adjust a segmental orientation and position ofeach of the plurality of actuators.

The motion system further comprises inertial measurement unit (IMU)sensors to estimate the segmental orientations, positions and forces ofthe actuators. Output signals of the sensors are fed into the input unitof the central controller. The processing unit processes the receivedsignals from the sensors, computes the length and orientation of thekinematic legs of the actuators and provides output signals to the atleast one driver of the least one of the actuators to adjust the length,orientation and the trajectory of the plurality of kinematic legs ofsuch actuator in real time. The IMU sensors comprise a sensor algorithmprogramed to record a 3-axis acceleration, 3-axis gyro, 3-axismagnetometer and a height (barometric pressure) in real time along withcorrected roll, pitch and yaw of the movable plate

In another aspect, the central controller compares the signals obtainedfrom the IMU sensors against a predetermined data set provided by anoperator and generates output signals to the at least one driver of theat least one actuator.

In one aspect, the motion system comprises a linking element to connecttwo of the neighboring actuators. The linking element can be a rigidbar. The rigid bar can connect together one pair of neighboringactuators and an another linking element can connect another pair ofneighboring actuators. The another linking element can be a linkingdamper.

In one aspect, the motion system further comprises a plurality ofmicrocontrollers that are in communication with the central controller.The plurality of microcontrollers are programmed to handle low-levelcalculations to drive the kinematic legs of the actuators for a giventime-variant trajectory while the central controller conducts high-levelcommands to estimate the orientation and position of the actuator overtime.

In one aspect, a reinforced actuator is provided. The reinforcedactuator comprises a Stewart platform with a base plate, an upper plate,a plurality of adjustable legs pivotally connected to the upper plateand the base plate, and a driver in communication to the plurality oflegs. The leg's driver is configured to adjust a length, orientation andvelocity of each of the plurality of legs. The actuator is reinforcedwith a damper that is rotatably connected to the upper plate and thebase plate of the Stewart platform. The damper comprises a driver thatadjusts in real time stiffness of the damper and thus the mobility ofthe actuator. The actuator further comprises a controller that is incommunication with the driver of the legs and the driver of the damper.The controller is configured to calculate a position, orientation and amotion trajectory of the plurality of legs and adjust in real time thelength, orientation and the trajectory of the plurality of legs and astiffness of the damper.

In addition to the aspects and embodiments described above, furtheraspects and embodiments will become apparent by reference to thedrawings and study of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Throughout the drawings, reference numbers may be re-used to indicatecorrespondence between referenced elements. The drawings are provided toillustrate example embodiments described herein and are not intended tolimit the scope of the disclosure. Sizes and relative positions ofelements in the drawings are not necessarily drawn to scale. Forexample, the shapes of various elements and angles are not drawn toscale, and some of these elements are arbitrarily enlarged andpositioned to improve drawing legibility.

FIGS. 1A and 1B are perspective views of Stewart platform actuator witha damper according to an embodiment of the present invention.

FIG. 2A is a perspective view of an example of a damper for reinforcingan actuator of FIGS. 1A and 1B.

FIG. 2B is a perspective view of the damper of FIG. 2A with atransparent housing to provide view of a movable member.

FIG. 3A is a perspective view of a motion system with two Stewartplatform actuators with a flexible link between the two actuators.

FIG. 3B is a side view of a motion system with two Stewart platformactuators with a damper linking the two actuators.

FIG. 4 is a cross-sectional side view of another example of areinforcing damper of the present invention.

FIG. 5 is a perspective view of an example of a lower limb exoskeletonmobility assistive device of the present invention.

FIG. 6 is a perspective view of an example of a full body robot madewith a Stewart platform based actuators.

FIG. 7 is a diagram showing a motion system with a motion capture unit,a motion simulation unit and a motion actuation unit.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

A Stewart platform actuator (also called hexapod) can be used in motionsimulators or robotic structures to mimic in a controllable mannercertain motions. For example, Stewart platforms can be used inexoskeleton robots to closely reproduce the natural movements/gait ofhuman body. The Stewart platform actuator comprises a body with a topplate connected to a base plate by six individual struts (kinematiclegs). Each of these six legs is connected to both plates by universaljoints. In this architecture, the load is distributed among severalparallel kinematic chains which thereby provide a high nominalload-to-weight ratio with high positioning accuracy and speed. Thestress induced in each link is mostly of a traction-compression naturewhich is quite suitable for linear actuators and therefore contributesto the rigidity of the manipulator.

The Stewart (hexapod) based actuators can be used in motion systems suchas, an exoskeleton robot or full body robot to mimic human gait or anyother desired movement. For example, such motion system (examplesillustrated in FIGS. 5 and 6) can have a modular body having a pluralityof Stewart platform actuators stuck to each other and arranged in thedesired configuration, shape and size. Each of the actuators isindependently control by controlling a length/orientation and speed ofeach of the legs in the actuators. The actuators can be joined to eachother directly or can be connected with a flexible or rigid linkingelement. In one motion system some of the actuators can be stuck to eachother directly while others can be connected with a linking element. Forexample, FIG. 6 shows a full body robot having a plurality of actuators(e.g. group of actuators indicated with reference number 60) that areconnected to each other directly (no linking elements) while some of theactuators (e.g. group of actuators indicated by reference 62) can beconnected with linking elements. The actuators in the motion system canbe used as joints or bony/muscular structure.

The Stewart platform based actuator can be described with reference toFIGS. 1A and 1B that illustrate an example of the hexapod (Stewartplatform with six kinematic legs) based actuator 100. The actuator 100comprises an upper plate 10 and a base plate 12 that are connected in anarticulated manner by a plurality of legs 14. The illustrated example ofthe actuator 100 is defined as a hexapod which utilizes six kinematiclegs 14 that in combination, control a selected position of the uppermovable plate 10 within six degrees of freedom relative to the baseplate 12 (three translation axes and three rotation axes), at the sametime. Alternate designs can include more than six legs 14 or less thansix legs 14 without departing from the scope of the invention. Aplurality of connecting joints 13 pivotally attaches the legs 14 to thebase 12. For example, the joints 13 can be a U-joint ball receptorformed at an inner surface of the base 12 and a U-joint ball located ata lower end 14 a of the leg 14, so that the leg 14 can be pivotallyattached to the base 12. Alternatively, the leg 14 can be rotatablyattached to the base 12 using any other universal joint such as a singleU-joint, a double U-joint, a pin and block U-joint, a needle bearingU-joint or any other known means for rotatably connecting the lower end14 a of the leg 14 to the base 12. The upper plate 10 comprises an innersurface, an outer surface and a plurality of connecting joints 17 (seeFIG. 1B) that rotatably connect an upper end 14 b of the leg 14 to theupper plate 10. The connecting joints 13 and 17 can be of the same typeor different type without departing from the scope of the invention.When used herein, the phrase “rotatably attached”, when describing theattachment between two or more parts or elements, means that thereferenced parts or elements are attached to one another in such amanner that allows rotation thereinbetween. The base plate 12 can bedimensioned to have a surface area that is greater than, less than orequal to the surface area of the upper plate 10. The actuator 100 can beflipped around so that its upper plate becomes a base plate and viceversa without departing from the scope of the invention as long as thereare two plates connected with a plurality of kinematic legs. The upperplate 10 and the base 12 may be constructed in various manners, out ofvarious materials, and in various shapes and sizes. For example, theymay consist of one-piece or multiple-pieces.

The legs 14 are positioned between the base plate 12 and the upper plate10. The legs 14, in combination, control the position of the upper plate10 within six degrees of freedom relative to the base plate 12 (and viceversa can control the position of the base plate 12 within six degreesof freedom relative to the upper plate 10). Each of the legs 14 ispreferably similar in construction to one another. The legs 14 areadjustable (length-wise and orientation-wise) and controllable using acontroller 15. Each of the legs 14 can be adjusted (length ororientation) independently by the other legs 14 of the actuator 100. Inthe example illustrated in FIG. 1B, each of the legs 14 comprises a rod16 a and a tube 16 b that is shaped and sized so that the rod 16 a canslide partially within the tube 16 b. The rod 16 a and the tube 16 b ofthe leg 14 are telescopically connected. The length and orientation ofeach of the legs 14 can be adjusted by sliding or rotating the rod 16 ain relation to the tube 16 b. The actuator 100 can further comprise sixdrivers 19 in communication with each of the legs 14 to drive each ofthe legs 14 in linear or rotational fashion. The driver 19 can beelectrical, hydraulic/pneumatic or mechanical driver. Each of thedrivers 19 is in communication with the controller 15. FIG. 1A showsonly one driver 19 (for clarity only) that is in communication with onlyone of the legs 14, however the actuator 100 comprises plurality ofdrivers to drive each of the legs 14 independently from each other. Thecontroller 15 is configured to accurately control length and orientationof each leg 14. The controller 15 can comprise an input/output unit anda processing unit. For example the controller 15 can be a 32 bit systemwith 6-axis control, 100BaseT and USB 2.0 interface, 6 quadraturedecoding channels and smart limit switch support. The controller 15 canbe located remotely from the actuator 100 and can be in communicationwith the drivers 19 of the legs 14.

In one implementation, the actuator 100 can further comprise a pluralityof sensors 23, such as inertial measurement unit (IMU) sensors that cancomprise a tri-axial accelerometer, tri-axial rate gyro and tri-axialmagnetometer. The sensors measure the position of each of the legs 14 inreal time and provide such information to the controller 15 as an input.FIG. 1A shows only one sensor 23 for clarity reasons, however it shouldbe understood that the actuator 100 can comprise a plurality of sensors23 position at the actuator 100 and/or remotely from it. Based on suchinput the controller 15 can make calculations of the lengths,orientation and velocities of each of the legs 14 in real time and canprovide output signals (step/direction signals) that can be sent to theleg's drivers 19 (e.g. linear axis stepper motor or DC servo motor) toadjust the length and orientation of the legs 14 of the actuator 100. Inone implementation, the leg's driver 19 can be any suitable electrical,pneumatic, hydraulic or mechanical driver that can adjust the length,orientation and/or speed of the legs 14 in real time based on the inputreceived from the controller 15. In addition the controller 15 cancomprise a signal conditioning circuit. Outputs from the sensors 23 canbe processed by the signal conditioning circuit before being processedby the control processing unit. Output from the processing unit istransferred to the power drive to provide the required drive signal(e.g. voltage) to the leg's drivers 19.

In one implementation, the sensors 23 can be omitted and the controller15 can be designed such that the user can provide inputs that allowchanging of the desired conditions or user preferences of motionconditions (flat surfaces, slopes, etc.). In another implementation,such input can be fed into the controller 15 by the sensors 23 and theuser. So the controller 15 can receive input from the one or moresensors 23 and/or as user inputs and can provide commands for the leg'sdrivers 19 based on such input. The sensors 23 can be IMU sensors thatcan record 3-axis acceleration, 3-axis gyro, 3-axis magnetometer andheight (barometric pressure) in real time along with corrected roll,pitch and yaw using a proprietary sensor algorithm. The output of theIMU sensors 23 can be fed directly into the controller 15. Thecontroller 15 can then compare such input data against a predetermineddata set (e.g. set up by the user) and can then adjust, if necessary,the output signals transferred to the leg's drivers 19. In oneimplementation, every leg 14 can comprise a separate microcontroller incommunication to the controller 15. In one implementation, only selectedlegs 14 can be in communication with the controller 15 while the restare passive or compliant, such as they are manually adjusted but are notmotorized or remotely driven.

In the example of the actuator 100 illustrated in FIGS. 1A and 1B theactuator 100 is further reinforced with a damper 20. For example, thedamper 20 can be positioned between the upper plate 10 and the base 12and can be configured to adjust the stiffness of the actuator 100. Thedamper 20 can be configured to increase the payload capacity and canprovide high stiffness, speed, and load capability of the actuator 100.In one implementation, the damper 20 can be a Magnetorheological (MR)damper or an Electrorheological (ER) damper or any other suitabledamper. A MR damper uses magnetorheological (MR) materials as dryparticles or particles dispersed in fluid to provide controllabledamping forces. The particles are comprised of magneto-soft particles.For example, the housing of the damper can be filled with suspension ofmicron-sized magnetizable particles (e.g. iron particles) in anappropriate carrier fluid. The MR fluid is controlled by a magneticfield, usually using an electromagnet. This allows the dampingcharacteristics of the MR damper to be continuously controlled byvarying the power of the electromagnet. When the MR fluid is subjectedto a magnetic field, the iron particles align along the magnetic linesthus solidifying the suspended iron particles and restricting the fluidmovement. The damping force is only dependent on the magnetic fieldapplied to the MR fluid/particles and can be adjusted up to 1,000 timesin a second. This means that the MR dampers can respond in real time andcan be highly and accurately controllable. The polarizable particles arethe basic difference between ER and MR dampers. ER damper uses smallerparticles that polarize when directly exposed to an electric current. MRdamper uses larger particles that polarize when surrounded by a magneticfield. Any other known suitable damper can be used with the platform 100to increase its payload capacity and stiffness.

FIGS. 2A and 2B show in details an example of the damper 20. The damper20 can have an elongated body with a first end 20 a configured to beconnected to one of the plates of the actuator 100 (e.g. plate 10), anda second end 20 b configured to be connected to the opposite plate ofthe actuator 100 (e.g. base 12). A joint 201 (e.g. a U-joint ball)located at the first end 20 a can be used to pivotally attached to aU-joint ball receptor 202 that is attached to the upper plate 10 of theactuator 100. Similarly, a U-joint ball 203 located at the second end 20b can be used to pivotally attached to a U-joint ball receptor 204 thatis attached to the base 12 of the actuator 100. Alternatively, thedamper 20 can be attached to the upper plate 10 and the base 12 usingany other universal joint configured to pivotally attach the damper 20to the respective plates 10, 12 of the actuator 100. The damper 20 cancomprise a housing 210 that contains a magnetically controllableparticles/fluid and a movable member 206 (FIG. 2B) mounted for movementthrough the particles/fluid in the housing 210. In the illustratedexample, the movable member 206 is a piston that is connected to thefirst end 20 a of the damper 20 through a rod 208. The housing 210 ishollow having an inner bore with a diameter slightly bigger than anouter diameter of the piston 206 so that the piston 206 and the housing210 can move in relation to each other in linear or rotatable fashion.The damper 20 can further comprise one or more bearings and seals (notshown) to prevent any fluid leakage out of the housing 210. A smallvolume of magnetically controllable fluid can be provided in the innerbore of the housing 210. A magnetic field generator 21 (see FIG. 1A)produces a magnetic field for directing the magnetic flux to desiredregions of the MR fluid. For example, the magnetic field generator cancomprise an electromagnetic coil and a power circuit in communicationwith the coil to generate magnetic field to increase the stiffness ofthe damper 20. In one embodiment, the electromagnetic coil can belocated inside the piston 206. The rod 208 can be hollow and can beconfigured to house a power line between the electromagnetic coil and apower source so that when the power source is on, the coil is energizedgenerating a magnetic field. In another embodiment, the electromagneticcoil can be mounted around the housing 210. When the coil is energizedby applying a voltage, the fluid in the housing 210 becomes solid thuslocking together the piston 206 and the housing 210. By placing thedamper 20 between the upper and base plates 10, 12 of the actuator 100,the stiffness of the overall actuator is controllable. The damper 20 canadjust it's length to accommodate the motion of the upper plate 10 withrespect to the base plate 12 of the platform 100 meaning that when thepower source is turned off and the coil is de-energized the piston 206can freely move (linearly or in rotational fashion) in relation to thehousing 210 in accordance to the movement of the upper plate 10 and/orthe base plate 12. Additionally and alternatively, the damper 20 can bein communication with a controller that can be configured to control thedriver of the damper (i.e. magnetic field generator 21) and thus cancontrol the magnetic field and the stiffness of the damper 20 in realtime.

In one implementation, one or more (or all) of the legs 14 can beprovided with a housing enclosing at least a portion of the legs 14. Acoil can be provided around the housing so that the legs 14 can have afunction of a damper when such coil is energized to provide a magneticfield to a MR/ER particles/fluid provided in the housing. The controllerthat controls the damper 20 can be separate or the same as with thecontroller 15 of the actuator 100. For example, based on the data fedfrom the sensors 23 or inputted by the user the controller 15 can sendoutput signals to the leg's drivers 19 and at desired time to thedamper's driver 21 to adjust the stiffness (e.g. magnetic field) of thedamper 20. Person skilled in the art would understand that the damper 20can have different configuration than the one illustrated in the FIGS.2A, 2B without departing from the scope of the invention. For example,FIG. 4 shows an example of a damper in which instead of piston 206 aspring element is utilized.

FIGS. 3A and 3B depict a motion system 1000 that comprises at least twoStewart platform based actuators 100. FIGS. 3A and 3B show two actuators100 connected with a linking element 2000, however the linking elementcan be omitted and the motion system 1000 can include at least twoactuators 100 connected one to another directly with no linking elementin between. In the illustrated example at FIG. 3A the linking element isone or more springs 2001 while FIG. 3B shows a linking element that is adamper that is similar to the damper 20 described herein above withreference to FIGS. 2A and 2B. Person skilled in the art would understandthat the linking element 2000 connecting any two actuators 100 can beany rigid or flexible element with or without dampening element.

In the example illustrated in FIG. 3A, the link 2000 can be a spring2001 connecting the two actuators 100. By connecting the two actuators100 together with the spring 2001 the relative motion of the twoactuators 100 with respect to each other can be softened while stillpreserving a degree of stiffness. In the embodiment illustrated in FIG.3B, the linking element can been updated to add dampening element to thespring 2001 (becoming a linking damper 2005) by surrounding the spring2001 with a housing, i.e. a sleeve 2002, that contains MRparticles/fluid (see FIG. 4). The sleeve 2002 can be made of any othersuitable material and can envelop the spring 2001 in a fluidly tightmanner so that no fluid can leak out of the sleeve 2002. In theillustrated example the sleeve 2002 has multiple folds or any otherelastic configuration so that its length can be adjusted to accommodatethe spring 2001 in its extended and/or retracted position. A coil 2004(see FIG. 4) can be wrapped around the spring 2001 or the sleeve 2002and the MR particles/fluid can be inserted in the sleeve 2002, such thatthe spring's stiffness can be controlled by a voltage applied to thecoil 2004. The coil 2004 is in electrical communication with a powersupply (not shown). The linking damper 2005 and each of the actuators100 can be control by the system's central controller (not shown) thatindependently control and adjust theposition/orientation/velocity/stiffness of each of the actuators 100 andthe linking damper 2005 in real time to mimic natural or requiredmotion. The adjustable linking dampers 2005 and/or other types offlexible or rigid linking elements 2000 in addition to the actuators 100can help with the load distribution as well as mimicking the naturalflexibility of the body links in extensions and contraction. In oneembodiment, each of the actuators 100 in the motion system 1000 and/oreach of the linking element/damper can be controlled by a separatemicrocontroller what are in communication with the central systemcontroller. The high-level commands can be made by the centralcontroller to estimate position of each of the actuators 100 over timewhile the microcontrollers can be provided to handle low-levelcalculations required to drive the legs 14 of the actuators 100 for agiven desired trajectory which may be time variant.

The motion system 1000 can comprise more than two actuators 100 that canbe connected with the linking elements/dampers or can be connected toeach other directly with no linking elements in between. In oneimplementation, the motion system 1000 can comprise plurality ofactuators 100 where some of the actuators 100 can be stuck to each otherdirectly while others can be connected with linking elements. Eventhough the motion system 1000 illustrated in FIGS. 3A and 3B comprisesactuators 100 reinforced with damper 20, person skilled in the art wouldunderstand that that the actuators 100 can be Stewart platform basedactuators with no reinforcing damper 20. In fact, FIGS. 5 and 6 show twoexamples of a motion system 1000 in which the actuators 100 are withoutreinforcing damper 20.

FIG. 5 shows a motion system 5000 that is a lower limb exoskeletonmobility assistive device with four actuators 100 connected with linkingelements 2000. The linking elements can be rigid bars or flexiblesprings or a combination thereof. In some embodiments some or all of thelinking elements can be a damper as the one described with reference toFIGS. 2-4. The advantage of using actuators 100 in human exoskeletalsuits is that the actuators 100 have a high strength and can change thelength/stiffness thereby reducing pressure points. Such exoskeletal suitis anti-chafing and can change the length during usage. For example,such exoskeletal suit can change the length depending on the performedmotion by changing the length and/or orientation of the legs 14 of theactuators 100. Additionally and alternatively, the motion system 5000can have a high adjustability of the structure design to accommodatedifferent wearers by adjusting the length and design of the actuators100 and the linking elements 2000.

In one possible application, the system 1000 can be used in a full bodyhexapod based robot—hexosapian 6000, an example of which is illustratedin FIG. 6. As shown in FIGS. 5 and 6 the multiple actuators 100 can actas joints (e.g. hip, knee, ankle) or skeletal/muscular structure. Someof the actuators 100 in such motion systems can be linked withadjustable flexible links or rigid links or linking dampers (e.g.linking element 600), while some of the actuators 100 can be connecteddirectly with no linking elements in between. For example FIG. 6 showsthe full body robot 6000 in which at least one group of three actuators60 is connected with no linking elements in between. The group 60comprises three actuators that are connected together directly with nolinking elements. The upper plate of the actuators 601 and 602 isadapted to act as a common upper plate for the both actuators. Asillustrated in FIG. 6, some of the actuators in the same motion system6000 can be connected with linking element (e.g. group of actuators 62comprising actuators 601 and 603 connected with the linking element600).

The damper's controlling unit can be the same or separate unit and canbe incorporated in the actuator's controller 15 or system's centralcontroller. In one implementation, the system's central controller cancomprise IMU sensors that can estimate necessary parameters, i.e.segmental orientations, positions and forces of the actuators 100 and/orthe connecting elements/dampers 2000, 2005. The central controller canbe capable of computing accurately the orientation estimations by fusingraw signals obtained from the sensors (i.e. signals obtained from atri-axial accelerometer, tri-axial rate gyro and tri-axial magnetometer)accurately calculating the lengths and velocities of each of the legs 14in each of the actuators 100 of the motion system 1000 and convert suchsignals into step/direction signals that can be sent to the leg'sdrivers 19. In one implementation, the central controller can receivethe input data from a user/operator. By employing IMU sensors thebalance stability of the system 1000 can be quantified and potentialfalls can be detected.

Additionally and alternatively, the system 1000 can comprise a motionsimulating unit 3001 (FIG. 7) that is in communication with a motioncapture unit 3002 and a motion actuation unit 3003 of the system 1000.The motion capture unit 3002 comprises a plurality of motion sensors.For example, the motion sensors can be surface electromyography (sEMG)sensors that can be positioned remotely from the system 1000. Thesignals from the motion sensors are process by the motion simulatingunit 3001 which then provides signals to the motion actuation unit 3003.The motion actuation system 3003 can be the motion system 1000 with theplurality of actuators 100. So, the signals from the motion sensors areprocess by the motion simulating unit 3001 which then provides signalsto the central controller of the motion system 1000 to accordinglyactuate the actuators 100 to mimic the predetermined motion trajectorythat was simulated by the simulating unit 3001. In one implementationthe plurality of sensors (sEMG sensors) can be located to a trainer(e.g. a human being). In such implementation, the motion sensors locatedat a specific parts of the human body can detect the bioelectricalpotential generated by muscle cells and the signals can be sent to asimulating unit 3001 to analyze and detect the activity of the wearer'starget muscles (and his/her intention). The signals from the simulatingunit 3001, and in some implementations signals from the sensors (motioncapture unit 3002) can be fed into the motion actuation unit 3003 (e.g.the system's central controller) as input to generate output signals(driving signals) to the actuators 100 of the system 1000 to control themotion (movements) of the system 1000. For example the motion simulatingsystem illustrated in FIG. 7 can be used in applications where thetrainer can remotely control the movement of a robotic structure.

Additionally and alternatively, a safety assembly can be provided toprotect against potential falls which may occur due to reasons such ascollision with objects, slippery surfaces, etc. The safety assembly maycomprise a rechargeable polyurethane foam bag, an airbag system or anyother system used for protecting fragile structures and mechanisms. Thesafety assembly is in communication with the controller that can triggersuch safety mechanism based on the input it receives from the sensors(IMU sensors).

While particular elements, embodiments and applications of the presentdisclosure have been shown and described, it will be understood, thatthe scope of the disclosure is not limited thereto, since modificationscan be made by those skilled in the art without departing from the scopeof the present disclosure, particularly in light of the foregoingteachings. Thus, for example, in any method or process disclosed herein,the acts or operations making up the method/process may be performed inany suitable sequence and are not necessarily limited to any particulardisclosed sequence. Elements and components can be configured orarranged differently, combined, and/or eliminated in variousembodiments. The various features and processes described above may beused independently of one another, or may be combined in various ways.All possible combinations and subcombinations are intended to fallwithin the scope of this disclosure. Reference throughout thisdisclosure to “some embodiments,” “an embodiment,” or the like, meansthat a particular feature, structure, step, process, or characteristicdescribed in connection with the embodiment is included in at least oneembodiment. Thus, appearances of the phrases “in some embodiments,” “inan embodiment,” or the like, throughout this disclosure are notnecessarily all referring to the same embodiment and may refer to one ormore of the same or different embodiments. Indeed, the novel methods andsystems described herein may be embodied in a variety of other forms;furthermore, various omissions, additions, substitutions, equivalents,rearrangements, and changes in the form of the embodiments describedherein may be made without departing from the spirit of the inventionsdescribed herein.

Various aspects and advantages of the embodiments have been describedwhere appropriate. It is to be understood that not necessarily all suchaspects or advantages may be achieved in accordance with any particularembodiment. Thus, for example, it should be recognized that the variousembodiments may be carried out in a manner that achieves or optimizesone advantage or group of advantages as taught herein withoutnecessarily achieving other aspects or advantages as may be taught orsuggested herein.

Conditional language used herein, such as, among others, “can,” “could,”“might,” “may,” “e.g.,” and the like, unless specifically statedotherwise, or otherwise understood within the context as used, isgenerally intended to convey that certain embodiments include, whileother embodiments do not include, certain features, elements and/orsteps. Thus, such conditional language is not generally intended toimply that features, elements and/or steps are in any way required forone or more embodiments or that one or more embodiments necessarilyinclude logic for deciding, with or without operator input or prompting,whether these features, elements and/or steps are included or are to beperformed in any particular embodiment. No single feature or group offeatures is required for or indispensable to any particular embodiment.The terms “comprising,” “including,” “having,” and the like aresynonymous and are used inclusively, in an open-ended fashion, and donot exclude additional elements, features, acts, operations, and soforth. Also, the term “or” is used in its inclusive sense (and not inits exclusive sense) so that when used, for example, to connect a listof elements, the term “or” means one, some, or all of the elements inthe list.

The example calculations, simulations, results, graphs, values, andparameters of the embodiments described herein are intended toillustrate and not to limit the disclosed embodiments. Other embodimentscan be configured and/or operated differently than the illustrativeexamples described herein.

1. A motion system comprising: a plurality of Stewart platform basedactuators connected one to each another forming a desired modularconfiguration, the plurality of Stewart platform actuators comprising anupper plate, a base plate, a plurality of kinematic legs pivotallyconnected to the base plate and the upper plate extending thereinbetween and at least one driver in communication with the plurality ofkinematic legs configured to independently drive each of the pluralityof kinematic legs to change length, orientation and/or speed of thelegs, wherein a coordinated drive of the plurality of legs moves one ofthe plate within six degrees of freedom relative to the other plate; anda central controller having an input unit, a processing unit and anoutput unit and being in communication with the at least one driver ofeach of the plurality of actuators to independently control length,orientation and/or speed of each of the plurality of kinematic legs ofeach of the plurality of actuators to adjust a segmental orientation andposition of each of the plurality of actuators.
 2. The motion system ofclaim 1, wherein the central controller comprises inertial measurementunit (IMU) sensors to estimate the segmental orientations, positions andforces of the actuators.
 3. The motion system of claim 2, wherein outputsignals of the sensors are fed into the input unit of the centralcontroller, the processing unit processes the received signals from thesensors, computes the length and orientation of the kinematic legs ofthe actuators, and provides output signals to the at least one driver ofthe least one of the actuators to adjust the length, orientation and thetrajectory of the plurality of kinematic legs of such actuator in realtime.
 4. The motion system of claim 3, wherein the IMU sensors compriseat least one of a 3-axial rate gyro, a 3-axial accelerometer and a3-axial magnetometer.
 5. The motion system of claim 4, wherein the IMUsensors comprise a sensor algorithm programed to record a 3-axisacceleration, 3-axis gyro, 3-axis magnetometer and a height (barometricpressure) in real time along with corrected roll, pitch and yaw of themovable plate.
 6. The motion system of claim 3, wherein the centralcontroller compares the signals obtained from the IMU sensors against apredetermined data set provided by an operator and generates outputsignals to the at least one driver of the at least one actuator.
 7. Themotion system of claim 1, further comprising a linking elementpositioned between at least one pair of two neighboring actuatorsthereby connecting them, the linking element being selected from a groupof a rigid bar, a spring and a linking damper.
 8. The motion system ofclaim 7, wherein the linking element comprises a rigid bar.
 9. Themotion system of claim 7, wherein the rigid bar connects together onepair of neighboring actuators and an another linking element connectsanother pair of neighboring actuators, the another linking element beinga linking damper.
 10. The motion system of claim 1, further comprising areinforcing damper rotatably connected to the upper plate and the baseplate of at least one of the actuator, the reinforcing damper having adriver and a controller in communication with the reinforcing damperdriver to control and adjust the stiffness of such actuator inreal-time.
 11. The motion system of claim 1, wherein at least one of theplurality of kinematic legs is a reinforcing Magnetorheological (MR)damper.
 12. The motion system of claim 1, further comprising a pluralityof microcontrollers that are in communication with the centralcontroller, wherein the plurality of microcontrollers are programmed tohandle low-level calculations to drive the kinematic legs of theactuators for a given time-variant trajectory while the centralcontroller conducts high-level commands to estimate the orientation andposition of the actuator over time.
 13. The motion system of claim 1,wherein the central controller further comprises a signal conditioningcircuit.
 14. A reinforced Stewart platform actuator comprising: an upperplate; a base plate; a plurality of kinematic legs pivotally connectedto the base plate and the upper plate extending therein between; atleast one driver in communication with the plurality of kinematic legsand configured to independently drive each of the plurality of kinematiclegs to change length, orientation and/or speed of the legs, whereincoordinated drive of the plurality of legs moves one of the plateswithin six degrees of freedom relative to the other plate; a damperrotatably connected to the upper plate and the base plate to reinforcedthe actuator, the damper having a driver in communication to the damperto adjust damper's stiffness in real-time; and a controller incommunication with the driver of the kinematic legs and the driver ofthe damper, the controller comprising a processing unit programmed toadjust in real time a length, orientation and trajectory of theplurality of kinematic legs and a stiffness of the damper based on areceived input data.
 15. The reinforced actuator of claim 14, whereinthe controller comprises inertial measurement unit (IMU) sensors toestimate a segmental orientation, a position and a stiffness of theactuator.
 16. The reinforced actuator of claim 15, wherein outputsignals of the sensors are fed into an input unit of the controller, theprocessing unit processes the received signals from the sensors,computes the length and the orientation of the kinematic legs of theactuator, and provides output signals to the at least one driver of theactuator to adjust the length, orientation and the trajectory of theplurality of kinematic legs in real time.
 17. The reinforced actuator ofclaim 15, wherein the IMU sensors comprise a sensor algorithm programedto record a 3-axis acceleration, 3-axis gyro, 3-axis magnetometer and aheight (barometric pressure) in real time along with corrected roll,pitch and yaw of the movable plate.
 18. The reinforced actuator of claim15, wherein the central controller compares the signals obtained fromthe IMU sensors against a predetermined data set provided by an operatorand generates output signals to the at least one driver of the actuatorto adjust the length, orientations and/or speed of the kinematic legs.19. The reinforced actuator of claim 14, wherein the damper is aMagnetorheological (MR) damper.
 20. The reinforced actuator of claim 14,wherein at least one of the plurality of kinematic legs is a reinforcingMagnetorheological (MR) damper.